This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Background: Twelve animals were treated Depo Provera intramuscularly (IM) to thin the wall of the vaginal mucosa. Methods: Five-week post treatment, the 12 animals were divided into two groups of 6 animals each (placebo and active compound) and were challenged with high dose of SHIVSF162p3 and SHIVSF33A mixture 30 minutes post 2ml gel vaginal application. Results/Discussion: This experiment is still in the early stages to determine the final outcome. However, in a double blind study, where the gels (compounds) are labeled, A and B preliminary results are: in Group A: 2/6 systemically infected, with viral blip detected in 1/4 that are not systemically infected and in Group B: 5/6 are systemically infected. The results are not statistically significant, P=0.242 (Fisher exact test).